Drawback chucking mechanism



EAMES? Aug, 2, 1923.

A. E. DRISSNER DRAWBACK CHUCKING MECHANI SM Filed May 1'? 1921 2 Sheets-Sheet 1 ummm ,2 Sheets-Sheet 2 M S I m l RWE EEQ NM1 SG.. www. RG Duw .WM EKd .Gm Ami WF A. R .D

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Patented Aug.. 2l, ld.

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@GMP 0E' CLLAND, GEIQ, A, CGRPORATIGN mi' 0m@ IDBAWBACK ,CHUCKING MECHANESM.

Application tiled may 17, 1921. Serial No. 470,478.

To all whom t my, camera: l

Be it known that I, -Y E. llnrssNnR, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga. and State of Ohio, have invented certain new and usefull Improvements in Drawback Chucking Mechanism, otwhich the following is a specification.

- rlhis invention. relates to chucking mechansni suh for 'instance as draw-back or pullhack chucking mechanism adapted to be used in connection with revolving or stationary spindles, such as are employed ,in multiple and slngle spindle automatic lathes, hand screw machines, bar forming machines, lathes, and othermachines, an object of the invention being to rovide an improved chucking mechanism o this class which can be easil and economically manufactured and will e eicient and eilective inv operation and durable and Aserviceable in all vreference bein use.

@ther objects of this invention will appear in the 'following description thereof, had to the accompanying drawings ormm 'part of this specification,

Awherein like re' erence characters .indicate correspondinq parts in the several views, and wherein lFig.'2 1s an-end -viewtaken substantially ,along the line 2 2 of lFi 1; Fig. 3 is a ln carrying out my invention,- lprovide in general improvedl oerating means for the chuck comprising a nger holder of such construction and so mounted with relatior'i to the spindle that the lingers pivoted tothe finger holder will not spread through centrifugal Jforce irrespective of the speed of revolution of the spindle.

In the present instance, the springs uti-y lized for retainin the lingers in normal position are carrie interiorly of the nger holder9 and as a result thedan r of theV Y springs becoming displaced or dying ed and' causing the lingers to spread is obviated, a disadvan prevalent inl many devices 'heretofore constructed, where the spr 1g. lis aside view partly inv (section, parts being broken away, illustrating one position of the chucking mechanism;

are mounted around the outside 'of the n gers.

Furthermore the finger holder is mounted for adjustment on the spindle, and hence the grip of the operating jaws of the chuck on the work may be varied merely by adjusting the position of the finger holder and thrust means relatively to the spindle.

Also in the present invention the linger holder and the *thrust ring, which is actuated by the movement of the fingers to operate the chucking mechanism, are mounted so as to^be axially shiftable one relatively to the other and so as to have their juxtaposed faces at all times in fixed and positive relation to each other, the one revolving with the other as one p1ece. As a result, each am or cnavnnnnn, curo, assren'oa 'ro run narrower. nenn thrust finger when actuated engages the thrust ring always at a predetermined point,

and in the present instance li utilize as bearing oints two small thrust pins mounted interlorly of the thrust ring to receive the thrust of the iin ers. It will be readily seen therefore, that y virtue of this construction, the only parts that must he hardened are the small thrust ends of the ngers.

ln many devices heretofore constructed vwhere the thrust ring used is not connected in fixed relation with Ilthe finger holder, the

pins and the hearing thrust ends of the fingers bear on diderent places of the thrust ring due to the fact that onerotates relatively to the other, and hence the thrust ring is very liable to become warped due to the diculty of hardening and grinding the thrust ring perfectly, causing onethrust finger to erform all the work in chucking and there y causing considerablestrain on the finger holders.

'ln `the present invention however the I thrust ring is not hardened but is provided with smaller hardened thrust receiving elements or pins extending thereinto and suitably secured thereto, so that these elements or pins not only resist the wear caused by the thrust of the fingers hutalso form the onlyi parts necessary to be replaced after y becomlng worn from longuse and operation. In many devices heretofore constructed, a

v.cover is` often provided for/housing the lingers and for holding the same from spreading due t0 centrifugal force, but in such case where the n ers are not constructled perfectly 'or exact y alike and the in the cover is not machined perfectly only,

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i drilled, each hole one linger is forced down by the cover, thereby causing the same to cramp and dig into the spindle.

Another disadvantage o f many chucking mechanisms heretofore constructed resides in the fact that the fingers when released are liable to strike the spindle and injure the same. In the present instance, the construction is such that when the fingers are forced by the springs to travel toward the spindle, the same are limited in their move ment relatively to the spindle thereby preventing the fingers from striking the spindle and consequently marring the same so that the sliding wedge is not hampered in its free movement over the spindle.

Referring to the drawings illustrating a preferred embodiment of my invention, the same comprises a spindle 1 mounted in suitable bushings 2 and 3. On the rear end of the spindle a finger holder 4 is mounted for adjustment as by means of threads, the -finger holder'bein normally held from movement on the splndle by means of a hollow set screw 5. In the outside face of the finger holder 4 slots 7 are machined to a predetermined depth and fingers or levers 6 are pivoted as by means of pins 6. These slots 7 are positioned diametrically opposite each other preferably on a perpendicular or vertical plane through the center line of the finger holder as illustrated in Fig. 2. Mount- -ed on the spindle 1 is a sliding wedge 8 suitably machined so as to slide freely over the spindle. The outside face of the finger holder 4 is counter-bored to a suitable diameter and th and a bushing 9 is forced therein. In the rear face of the finger holder 4 holes 10 of an desired diameter are eing preferably positioned thirty degrees from the horizontal center lone of the spindle and each hole beingacounter-bored at 11 for the reception of a spring 12 heldin position by a screw 13 placed in each of the holes. The springs 12 are retained-within the counter-bore 11 by virtue of the heads of the screws 13. The threaded ends of the screws v13 are preferably/turned to a smaller diameter than the body thereof and are screwed into suitable holes drilled in a thrust ring 14. Through the rear end of the screws 13 are drilled suitable holes 15 through which are placed cotter pins 15, It will be seen therefore,

'that by virtue of the screws 13 resiliently interconnecting the finger holder and the thrust ring the juxtaposed faces of these parts are maintained in constant and fixed i relation to each other, the resilient connection permitting axial movement of one relatively to the other. v

Into the thrust ring 14 at a suitable distance from thecenter thereof are drilled two holes 16, into which are placed and suitably secured hardened thrust pins 17. These 6 so that the same at all times in operation e will engage the ins.

As shown in igs. 1 and 2 the pins 17 extend through the ring 14 and register with the open bore 18, so that in order to remove them for replacement it is merely necessary to knock them out from the rear of the ring 14.

The outside face of the thrust ring 14 is machined so as to provide a counter-bore 18 and a second counter-bore 19 of smaller diameter and depth extending inwardly beyond the counter-bore 18. Through the center of the thrust ring 14 is drilled a hole .20 and against the shoulder of thesmall counter-bore 19 of the thrust ring 14 and suitably secured thereto as at 19a (Fig. 2) is located a pull tube disk 21, the same being axially drilled at 22 and counter-bored to a suitable depth to form a flange 23. W'ithin the spindle 1 is mounted a pull tube 24 threaded or otherwise connected to the chuck 25 as at 26, the rear end of the pull tubefhaving a flange fitting into the counterbore of the pull tube disk and secured to and cooperating with the flange 23 thereof. With reference to Figs. 1 and 4, it will be seen that the slot 7 is formed with a base 30 adapted to act as a stop for arresting the movement of the fingers relatively to the spindle. Thus the fingers, as shown in Fig. 4 are by virtue of the limiting means 30 prevented from striking the spmdle, and marring the same, which as hereinbefore stated, would result 1n interfering with the sliding movement of the wedge 8 over the spindle.

In the operation of my improved drawback chucking mechanism it will be readily seen that as the wedge 8 is forced by any suitable means to travel in the direction of the fingers 6, the conical'or curved face of the wedge will cause the fingers 6 to be forced outwardly, and this travel-of the wedge will be continued until the outer curved ends of the fingers rest on the fiat surface of the wedge, which holds them in a positive osition. As the fingers travel outwardly t e thrust ends 17a thereof engagethe thrustv pins 17 ofthe thrust ring forcin the ring rearwardly against the tension o the sprlngs. As the thrust ring 14 travels in this direction it carries with it the pull tube disk 21 and the pull tube 24, and by virtue of 'the connection of the pull tube j the chuck the sam@ is shifted'rearand the jaws thereof are closed for clamping the work. The jaws it will be understood are constructed in the usual manner with outer angular faces and adapted to be shifted inwardly'T by virtue of the usual wedging action. In order to release the chuck from the work the sliding wedge 8 is shifted in the opposite direction away ESG instaat 1 from the finger holder by any suitable means. During this travel of the'wedge the ngers travel down the curved faces thereof and as a result of the action' of the springs 12 the thrust ring is forced toward the linger holder thereby shifting the pull tube forwardly for releasing `the jaws' from the work. It willbe seen that' the springs`12 exert a positive and continuous action upon the thrust ring 14 and as a result, as the fingers are shifted inwardly toward the spindle the thrust ring is held firmly against the thrust ends 17a of the fingers, thus holding the fingers in place at all times and preventing4 the centrifugal force of the revolving spindle from throwing the fingers away from the spindleand causing the chuck to gri the work. v

(gf course it will be understood that the size of the springs 12 will be varied according to the speed of revolution of the spindle, the greater the speed of revolution the larger the springs used.' Hence, no matter at what speed the spindle revolves, the direct and positive action of the springs will overcome .the centrifugal force tending to throw the lingers outwardly.

t will also be observed that by mounting the springs 12 interiorly of the linger holder the danger of the springs il ing o'- and becoming displaced 1s entirely eliminated and furthermore by mounting the operating ngers interiorly of the linger holder greater durability and strength will be given to these arts.

Altlough l have described my invention in its preferred form, it is to be understood that l do not limit myself to the construcltion herein shown and described, except in so far as dened in the claims and embraced within the scope thereof.

ll claim as my invention:

1. The combination finger holding member, fingers carried therei by, means for shifting said fingers into engagement with the thrust means, thereby shitting said thrust means and member one relatively to the other in one direction and 'a resilient connection between said t rust means and member normally adapted to prevent relative rotational movement thereof and to shift said thrust means and member one relatively to the other in the opposite direction.

2. The combination of a thrust member and a. finger holding member shiftable relatively to each other in one direction, lingers carried by said holding member, and resilient means for interconnecting said members and having a part carried interiorly of each thereof and adapted to resist said relative shiftable movement of the thrust and finger holding member 3. The combination of a thrust memberand a finger holding member shiftable relabers one relatively to the Amember for ot thrust means, av

engaging the spring, one thereof held in4 teriorly of each member, said resilient means operative against theaction of said fingers. 4. The combination of a pair of relatively shifta'ble members including a iinger holdin member, a finger ivoted to said iin er ho ding member, a slidlinguwedge adapte to engage said finger for s 'fting said memother, and resilient means connected to said finger holding resisting the action of said finger. f

5. The combination of a thrust member and a inger holding member, resilient means connectin said members together and held interior y thereof, a finger pivoted to said holding member interiorly thereof, anda sliding. wedge adapted to engage -said finger for shifting said thrust member and holding member one relatively to the other, said members having their juxtaposed faces normally in fixed rotative relation to each other, and said resilient means operative to yshift said thrust member and holding member one relatively to the posite direction.

6. rlhe combination of thrust means a linger holder, means for shifting the finger and for shi ing said thrust means in one direction, and resilient means connected to said nger holder for resisting-such movement.

7. rl`he combination ot thrust means, a linger holder, a iinger carried thereby, means for shifting the finger and for shifting said thrust means in one direction, and resilient means connecting said nger holder and thrust means together interiorly thereof for resisting such movement.

8. The combination of thrust means, a finger holding member, resilient means connecting said means and member together and comprising a spring and a pin enga ing the spring, one thereof held interior y of each, a finger pivoted to said holding member, and a sliding wedge adapted to engage said finger for shifting said thrust means and holding ,member one relatively to the other in one direction, said resilient means operating to cause relative shittable movement thereof in the opposite direction.

9. The combination with a nger holder for a spindle, of a pivoted linger carried thereby, means for spreading said finger, and means for resisting the spreading of the linger and, comprising a memberV cooperating with the finger and resilient means other in the oplocated at one side of the spindle and ina finger carried there fy, I,

tei-connected with said finger holder and connected with said finger holder and said 10 said cooperating member. cooperating member, said cooperating mem- 10. The combination with a finger holder ber comprising a disk, and a hardened for a spindle, of a pivoted finger carried thrust member carried by said disk in po- 5 thereby, means for spreading said finger, sition to engage the linger.

and means for resisting the spreading of Signed at Cleveland, Ohio, this 29th day 15 the finger and comprising a, member coopof April, 1921.

erating with the linger and resilient means located at one side of the spindle and inter- ALFRED E. DRISSNER. 

